A series of consecutive antibiotic trials for suspected sepsis in granulocytopenic cancer patients began in 1969, and continues to the present. Initial evaluations proved the usefulness of carbenicillin and gentamicin and later trials, including a large multiinstitutional trial, indicated that carbenicillin (ticarcillin) plus gentamicin had the best efficacy-to-toxicity ratio of the three possible two-drug combinations of carbenicillin (ticarcillin), gentamicin and cephalothin. A high incidence of nephrotoxicity secondary to the combination of cephalothin and gentamicin was noteworthy. In the next trial, cephalothin plus amikacin in 93 consecutive patient-trials was not as nephrotoxic but was more nephrotoxic than any of the following two-drug combinations in 1976-1978. Ticarcillin plus gentamicin was compared to ticarcillin plus amikacin and ticarcillin plus netilmicin. In 183 consecutive patient-trials, the efficacy was high and the toxicity minimal. With the addition of early granulocyte transfusions for poor risk patients, a response rate of over 90% has been demonstrated in the past one and one-half years.